In vitro Evaluation of Antifungal Activity of Ageratum conyzoides, Basella alba and Mitracarpus villosus on the Strain of Lasiodiplodia theobromae in the Kisangani Region / D R Congo

Abstract

Background: Brown rot associated with Lasiodiplodia theobromae threatens cocoa production in the Kisangani region. Aims: Following our previous investigations on the in vitro evaluation of antifungal activity, this study focused on demonstrating the inhibitory effects of extracts from fresh and dry leaves of Ageratum conyzoides, Basella alba and Mitracarpus villosus against a strain of Lasiodiplodia theobromae, the fungus responsible for brown rot of cocoa pods in the Kisangani region. Methodology: This in vitro evaluation was conducted on PDA medium with six replicates. Four extracts from each plant studied were applied to half of the surface area of the culture medium. Results: The strain of L. theobromae was inhibited by up to 68.1% by the aqueous extract of B. alba, 60.0% by the ethanolic extract of A. conyzoides and 55.2% by the ethanolic extract of M. villosus (all obtained from dry leaves). Among the extracts from fresh leaves, only the aqueous (56.7%) and ethereal (51.1%) extracts of A. conyzoides showed high inhibition percentages compared with those of B. alba and M. villosus. Conclusion: The dry-leaf extracts showed high inhibition percentages, followed by the fresh-leaf extracts and, finally, the crude extracts after two days of incubation. Thus, in addition to the expected results, all the plants studied were active. The inhibitory effects could be higher for the secondary metabolites of the respective plants.